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1.
PAUL C. ADAMS 《Geographical review》1997,87(2):155-171
ABSTRACT. Computer networks are often described in terms that imply a virtual space or place: electronic frontier, cyberspace, and information superhighway have been used to indicate computer networks as a whole; cafés, dungeons, and virtual offices are some of the “places” people refer to as being in or on networks. The use of this language, which I collectively call “virtual-place metaphors,” indicates three broad metaphorical themes: virtual architecture, electronic frontier, and cyberspace. The metaphors encourage control, surveillance, and capitalist expansion through computer technologies—and also evasion and resistance through computer technologies. 相似文献
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Oxygen depletion in the shallow bottom waters of Mobile Bay, Alabama, and in adjacent nearshore and continental shelf waters, is shown to be directly related to the intensity of water column stratification. Low winds speeds are coincidental with the onset of water column stratification and the occurrence of hypoxic events. Hourly, daily, and seasonal changes in the relationship between percent oxygen saturation or oxygen concentration in the bottom waters and surface-bottom density differences indicate that the oxidized materials are recently formed, and not relic or overwintering carbon sources. The influence of density structure (water column stratification) in other oxygen-depleted coastal water masses is compared to Mobile Bay. 相似文献
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Concentrations and calculated fluxes of trace metals into Bermuda nearshore marine and lake sediments are presented. In areas affected by anthropogenic activity, metal profiles show surface sediment enrichments similar to those observed in North American and European lacustrine and estuarine sediments. Atmospheric fluxes of Cu, Zn and Pb into the lake sediments are higher than those of rural areas in North America. These high fluxes are assumed to be due to jet-fuel combustion. Sediment profiles in the Hamilton City area indicate increased anthropogenic input of Cu and Pb compared to other marine locations. 相似文献
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The reduction of sulfate by sulfate reducing bacteria in the anoxic zone is an extremely important process during early diagenesis of marine sediments. Our data from Great Bay, NH reinforce the proposal that the rate of sulfate reduction is directly proportional to the reactivity of the organic matter or the amount of readily metabolizable organic matter present in the sediment and, hence, the source of the organic material in the anoxic zone. It appears that organic matter rich in marine organic remains is more easily degraded in the anoxic zone and that sulfate reduction rates can vary considerably in an estuarine system where many types of organic material may be deposited. 相似文献
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Wm. Mansfield Adams 《Pure and Applied Geophysics》1965,61(1):113-122
Summary Direct access to the crust and the upper portion of the mantle may be achieved by letting a high temperature (>1100°C) reactor core melt the rock in which it is placed and fall through the resulting magma. Data gathering and retrieval seem feasible. A schematic design of the proposed instrument is given.There are many problems concerning the composition and conditions of the interior of the earth which will not be solved upon completion of the projectedMohole Project. Comparison of the continental crust with the oceanic crust, relative distribution of radioactivity under continents and oceans, and the investigation of the mantle itself require access to greater depths than the present drilling techniques permit. To achieve these aims, it is recommended that a dense, heatgenerating object (such as a nuclear reactor core) be placed in the top of a salt dome. The hot object would melt the salt and fall downward through the moten salt. The sinking object would pass out of the source salt bed into rock at such a depth, say 35 000 feet, that if a few percent of H2O is present at that depth, then a granitic rock would melt at about 700°C. However, encounter with SiO2 containing no water would require a much higher temperature of about 1700°C. The type of rock that actually exists immediately below the source salt bed is unknown, but it is probably not a granitic rock.Thermal considerations indicate that the hole will freeze shut after downward passage of the tool, leaving the tool inside a liquid bubble. If the tool can generate heat long enough to melt its way up, as well as down, it may be possible to obtain magma samples. Instrumentation for control and telemetry purposes appears extremely difficult. Initial emphasis is placed on attaining the depth of interest. 相似文献
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Hydrogeological problems which involve the determination of lateral variations in structures or physical properties may be solved with electrical resistivity gradient profiling if there are significant variations in electrical resistivity, spatially or temporally. The method is explained, evaluated for sensitivity, compared with other methods, and applied to the location of volcanic dike zones that are impounding an anomalous water body near Schofield, Oahu, Hawaii. From the electrical soundings and other independent data, the lateral positions of the boundaries have been refined and their nature estimated. 相似文献
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Wm. Alexander Osborne Rebecca A. Hodge Gordon D. Love Peter Hawkin Ruth E. Hawkin 《地球表面变化过程与地形》2021,46(13):2656-2670
The passive, ambient sound above the water from a river has previously untapped potential for determining flow characteristics such as stage. Measuring sub-aerial sound could provide a new, efficient way to continuously monitor river stage, without the need for in-stream infrastructure. Previous published work has suggested that there might be a relationship between sound and river stage, but the analysis has been restricted to a narrow range of flow conditions and river morphologies. We present a method to determine site suitability and the process of how to record and analyse sound. Data collected along a 500 m length of the River Washburn during July 2019 is used to determine what makes a site suitable for sound monitoring. We found that sound is controlled by roughness elements in the channel, such as a boulder or weir, which influences the sound produced. On the basis of these findings, we collect audio recordings from six sites around the northeast of England, covering a range of flow conditions and different roughness elements, since 2019. We use data from those sites collected during storms Ciara and Dennis to produce a relationship between this sound and river stage. Our analysis has shown a positive relationship between an R2 of 0.73 and 0.99 in all rivers, but requires careful site selection and data processing to achieve the best results. We introduce a filter that is capable of isolating a river's sound from other environmental sound. Future work in examining the role of these roughness elements is required to understand the full extent of this technique. By demonstrating that sound can operate as a hydrometric tool, we suggest that sound monitoring could be used to provide cost-effective monitoring devices, either to detect relative change in a river or, after more research, a reliable stage measurement. 相似文献
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